There is absolutely tons of justified criticism of Assange. And there are tons more details about the crimes he reported on. But going into all of that requires a massive article that doesn't fit into a short comment; this stuff is documented elsewhere.

Despite all of Assange's many flaws, it boils down to this: he reported on war crimes, those crimes go unpunished and uninvestigated, but the US wants to punish Assange, severely, despite the fact that he is not American and never even set foot there.